Frontiers in Personalized Medicine PW-GW-AS DNA sequencing Reverse human genetics
Published Genome-Wide Associations through 06/2011, 1,449 published GWA at p 5x10-8 for 237 traits NHGRI GWA Catalog www.genome.gov/gwastudies
GWAS examples
UCSF Kaiser-Permanente N. Risch and P. Y. Kwok
UCSF Kaiser-Permanente 100,000 patients Genotype and telomere lengths many health traits
23andme
Hair Curl Asparagus smell Photic sneeze freckling
Research Discoveries at 23andme
Frontiers in Personalized Medicine PW-GW-AS DNA sequencing Reverse human genetics
Dopa (3,4-dihydroxyphenylalanine) responsive dystonia (DRD). hereditary dystonia with marked diurnal variation. begins in childhood. associated with mutations in genes encoding guanosine 5 - triphosphate (GTP) cyclohydrolase (GCH1), tyrosine hydroxylase (TH), and sepiapterin reductase (SPR). Bainbridge, M.N. et al. Whole-genome sequencing for optimized patient management. Sci. Transl. Med. 3, 87re3 (2011).
Fig. 1 Metabolic pathways of neurotransmitter production. Bainbridge M N et al. Sci Transl Med 2011;3:87re3-87re3 Published by AAAS
Clinical history fraternal twin pair. diagnosed with DRD at age 5. L-dopa was found to alleviate the clinical symptoms of dystonia in one twin. no identified deleterious variants in the TH or GCH1 genes. Sequencing of the SPR gene was not available. high-throughput sequencing used to interrogate the whole genomes of the male and female twins.
Mother Father Affected Affected
Results Three genes found with rare compound heterozygous mutations. ZNF544 encodes a computationally predicted zinc finger protein with no known function or targets C2orf16. SPR encoding sepiapterin reductase. SPR mutations seen in two previous families with DRD. recommended treatment of DRD caused by SPR mutations is with both the dopamine precursor L-dopa, which the twins were already prescribed, and the serotonin precursor 5-hydroxytryptophan (5-HTP), which the twins were not receiving. The male DRD patient reported improved focus in school, as well as improved coordination in athletics. Further, the male showed reduced drooling and hand tremor, and objective evidence for the latter was provided by serial handwriting samples. The female twin reported reduced frequency of laryngeal spasms, improved sleep and focus, and improved tolerance for exercise and was able to resume participation in sports after a 14-month absence. In the female DRD patient, there were also reduced choreiform movements of the tongue by objective physical examination.
Fig. 1 Metabolic pathways of neurotransmitter production. Bainbridge M N et al. Sci Transl Med 2011;3:87re3-87re3 Published by AAAS
Miller Syndrome Ng, S.B. et al. Exome sequencing identifies the cause of a Mendelian disorder. Nat. Genet. 42, 30 35 (2010).
Mother Father Affected
Family 1 Family 2 Family 3 Affected 1A Affected 1B Affected 2 Affected 3
Non-synonymous and Rare (~450/person) Two variants in the same gene (30/person) Same gene in 1A and 1B = 9 genes Same gene in 1A, 1B, 2 and 3 = DHODH dihydroorotate dehydrogenase Validate by sequence gene in 3 more cases.
Kabuki Syndrome Ng, S.B. et al. Exome sequencing identifies MLL2 mutations as a cause of Kabuki syndrome. Nat. Genet. 42, 790 793 (2010).
Kabuki syndrome Kabuki syndrome is a rare, multiple malformation disorder characterized by a distinctive facial appearance, cardiac anomalies, skeletal abnormalities, immunological defects and mild to moderate mental retardation. Six cases of parent-child transmission. Autosomal dominant disorder.
Mother Father Affected
Strategy Look for rare, loss-of-function protein coding changes in strongest patient See if find mutations in same gene in the second strongest patient, then third, then fourth, etc. After 4 patients, only one gene is common. MLL2 Retrospectively, see that MLL2 has suggestive mutations in 5 more patients. Ultimately, 9/10 patients had mutations in MLL2. For validation, found 26/43 patients had mutations in MLL2. 0/190 controls had mutations.
Genomic structure and allelic spectrum of MLL2 mutations that cause Kabuki syndrome The SET domain of MLL2 confers strong histone 3 lysine 4 methyltransferase activity and is important in the epigenetic control of active chromatin states.
Schinzel-Giedon syndrome Hoischen, A. et al. De novo mutations of SETBP1 cause Schinzel-Giedion syndrome. Nat. Genet. 42, 483 485 (2010).
Schinzel-Giedon syndrome Severe mental retardation, distinctive facial features, multiple congenital malformations (including skeletal abnormalities, genitourinary and renal malformations, and cardiac defects) and a higher-than-normal prevalence of tumors, notably neuroepithelial neoplasia. Sporadic, suggesting heterozygous de novo mutations in a single gene as the underlying mechanism.
Mother Father Affected
Strategy Look for rare, loss-of-function protein coding changes Only 1 gene shared in four patients SETB1. In all cases, mutations occurred de novo in patients and were absent from parents. Validated in 8/9 additional patients. Gain-of-function effect or dominant-negative effect
Frontiers in Personalized Medicine PW-GW-AS DNA sequencing Reverse human genetics
Reverse Human Genetics
DRD sequencing: Results Three genes found with rare compound heterozygous mutations. ZNF544 encodes a computationally predicted zinc finger protein with no known function or targets C2orf16. SPR encoding sepiapterin reductase.